Techniques for managing wireless communications over multiple carriers

ABSTRACT

Various aspects described herein relate to managing ultra low latency (ULL) communications over a plurality of component carriers (CC). A configuration for aggregating a set of CCs can be received, wherein the set of CCs includes at least a primary cell and a secondary cell. Based on the received configuration, at least the primary cell can be communicated with for legacy communications, wherein the legacy communications are based on a first transmission time interval (TTI) having a first duration. Based on the received configuration, the primary cell and the secondary cell can be communicated with for ULL communications, wherein the ULL communications are based on a second TTI having a second duration that is less than the first duration.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present application for patent claims priority to ProvisionalApplication No. 62/102,303 entitled “TECHNIQUES FOR MANAGING WIRELESSCOMMUNICATIONS OVER MULTIPLE CARRIERS” filed Jan. 12, 2015, which isassigned to the assignee hereof and hereby expressly incorporated byreference herein.

BACKGROUND

Described herein are aspects generally related to communication systems,and more particularly, to managing wireless communications over multiplecarriers.

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power). Examples of such multiple-access technologies includecode division multiple access (CDMA) systems, time division multipleaccess (TDMA) systems, frequency division multiple access (FDMA)systems, orthogonal frequency division multiple access (OFDMA) systems,single-carrier frequency division multiple access (SC-FDMA) systems, andtime division synchronous code division multiple access (TD-SCDMA)systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example of a telecommunicationstandard is Long Term Evolution (LTE). LTE is a set of enhancements tothe Universal Mobile Telecommunications System (UMTS) mobile standardpromulgated by Third Generation Partnership Project (3GPP). It isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lower costs, improve services, make use of newspectrum, and better integrate with other open standards using OFDMA onthe downlink (DL), SC-FDMA on the uplink (UL), and multiple-inputmultiple-output (MIMO) antenna technology. However, as the demand formobile broadband access continues to increase, there exists a need forfurther improvements in LTE technology. Preferably, these improvementsshould be applicable to other multi-access technologies and thetelecommunication standards that employ these technologies.

In wireless communication systems employing legacy LTE, a plurality ofUEs served by a particular eNodeB may be scheduled resources forcommunicating with the eNodeB over one or more channels usingtransmission time intervals (TTI) on the order of a 1 millisecondsubframe. As UE capabilities and demand for bandwidth increases, lowerlatency in communications may be desired.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

According to an example, a method of managing ultra low latency (ULL)communications over a plurality of component carriers (CC) is provided.The method includes receiving a configuration for aggregating a set ofCCs, where the set of CCs includes at least a primary cell and asecondary cell. The method also includes communicating, based on thereceived configuration, with at least the primary cell for legacycommunications, wherein the legacy communications are based on a firsttransmission time interval (TTI) having a first duration, andcommunicating, based on the received configuration, with at least one ofthe primary cell or the secondary cell for ULL communications, whereinthe ULL communications are based on a second TTI having a secondduration that is less than the first duration.

In other aspects, an apparatus for managing ULL communications over aplurality of CCs is provided. The apparatus includes at least oneprocessor, and a memory communicatively coupled with the at least oneprocessor. The at least one processor is configured to receive aconfiguration for aggregating a set of CCs, wherein the set of CCsincludes at least a primary cell and a secondary cell. The at least oneprocessor is also configured to communicate, based on the receivedconfiguration, with at least the primary cell for legacy communications,wherein the legacy communications are based on a first TTI having afirst duration, and communicate, based on the received configuration,with at least one of the primary cell or the secondary cell for ULLcommunications, wherein the ULL communications are based on a second TTIhaving a second duration that is less than the first duration.

In another example, an apparatus for managing ULL communications over aplurality of CCs is provided. The apparatus includes means for receivinga configuration for aggregating a set of CCs, where the set of CCsincludes at least a primary cell and a secondary cell. The apparatusalso includes means for communicating, based on the receivedconfiguration, with at least the primary cell for legacy communications,wherein the legacy communications are based on a first TTI having afirst duration, and means for communicating, based on the receivedconfiguration, with at least one of the primary cell or the secondarycell for ULL communications, wherein the ULL communications are based ona second TTI having a second duration that is less than the firstduration.

In other aspects, a computer-readable storage medium includingcomputer-executable code for managing ULL communications over aplurality of CCs is provided. The code includes code to receive aconfiguration for aggregating a set of CCs, where the set of CCsincludes at least a primary cell and a secondary cell. The code alsoincludes code to communicate, based on the received configuration, withat least the primary cell for legacy communications, wherein the legacycommunications are based on a first TTI having a first duration, andcode to communicate, based on the received configuration, with at leastone of the primary cell or the secondary cell for ULL communications,wherein the ULL communications are based on a second TTI having a secondduration that is less than the first duration.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to facilitate a fuller understanding of aspects describedherein, reference is now made to the accompanying drawings, in whichlike elements are referenced with like numerals. These drawings shouldnot be construed as limiting the present disclosure, but are intended tobe illustrative only.

FIG. 1 shows a block diagram conceptually illustrating an example of atelecommunications system, in accordance with aspects described herein.

FIG. 2 is a diagram illustrating an example of an access network.

FIG. 3 is a diagram illustrating an example of an evolved Node B anduser equipment in an access network.

FIG. 4 is a diagram illustrating example timelines for uplink bandwidthallocation.

FIG. 5 is a diagram illustrating an example system for managing ultralow latency (ULL) communications over a plurality of component carriers(CC) in accordance with aspects described herein.

FIG. 6 is a flow chart of an example method of communicating using a ULLand/or a legacy communication technology over a plurality of CCs inaccordance with aspects described herein.

FIG. 7 is a flow chart of an example method of configuringcommunications using a ULL and/or a legacy communication technology overa plurality of CCs in accordance with aspects described herein.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, modules, components,circuits, steps, processes, algorithms, etc. (collectively referred toas “elements”). These elements may be implemented using electronichardware, computer software, or any combination thereof. Whether suchelements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented with a “processing system”that includes one or more processors. Examples of processors includemicroprocessors, microcontrollers, digital signal processors (DSPs),field programmable gate arrays (FPGAs), programmable logic devices(PLDs), state machines, gated logic, discrete hardware circuits, andother suitable hardware configured to perform the various functionalitydescribed throughout this disclosure. One or more processors in theprocessing system may execute software. Software shall be construedbroadly to mean instructions, instruction sets, code, code segments,program code, programs, subprograms, software modules, applications,software applications, software packages, routines, subroutines,objects, executables, threads of execution, procedures, functions, etc.,whether referred to as software, firmware, middleware, microcode,hardware description language, or otherwise.

Accordingly, in one or more aspects, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can compriseRAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic diskstorage or other magnetic storage devices, or any other medium that canbe used to carry or store desired program code in the form ofinstructions or data structures and that can be accessed by a computer.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), and floppy disk where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Combinations of the above should also be includedwithin the scope of computer-readable media.

Described herein are various aspects related to allocating traffic dataresources in wireless communications. For example, an ultra low latency(ULL) wireless technology may be defined as based on a shortertransmission time interval (TTI) than an existing legacy wirelesstechnology. In one specific example, in long term evolution (LTE), whichis based on a TTI of 1 millisecond (ms) (1 subframe), ULL LTE can bedefined as based on a TTI having a duration less than a subframe (e.g.,one symbol, two symbols, a subframe slot, etc.). In this regard, a lowerlatency in communications is achieved by the shorter, more frequent TTI.It is possible, in some configurations, that the UE can be configured tocommunicate over a first component carrier (CC) using legacy LTE and ULLLTE resources, while also configured to communicate over a second CCusing legacy LTE resources and no ULL LTE resources or ULL LTE resourceand no legacy LTE resources (e.g. in uplink and/or downlinkcommunications). The UE can activate and deactivate ULL LTE over thesecond CC based on the legacy LTE resources, or vice versa (e.g., useULL LTE resources to activate/deactivate legacy LTE resources). The UEcan accordingly determine a latency for activating/deactivatingcommunications over the second CC based on whether legacy LTE or ULL LTEis enabled over the second CC. Moreover, the ULL LTE communications overthe second CC may correspond to carrying at least one of uplink and/ordownlink communications.

Referring first to FIG. 1, a diagram illustrates an example of awireless communications system 100, in accordance with aspects describedherein. The wireless communications system 100 includes a plurality ofaccess points (e.g., base stations, eNBs, or WLAN access points) 105, anumber of user equipment (UEs) 115, and a core network 130. Accesspoints 105 may include a scheduling component 302 configured toactivate/deactivate one or more CCs or allocate resources forcommunicating using legacy or ULL communications to one or more UEs 115,as described further herein. Similarly, one or more of UEs 115 mayinclude a communicating component 361 configured to receive informationrelated to activating/deactivating a CC and/or resources forcommunicating using legacy or ULL communications with the access points105. Some of the access points 105 may communicate with the UEs 115under the control of a base station controller (not shown), which may bepart of the core network 130 or the certain access points 105 (e.g.,base stations or eNBs) in various examples. Access points 105 maycommunicate control information and/or user data with the core network130 through backhaul links 132. In examples, the access points 105 maycommunicate, either directly or indirectly, with each other overbackhaul links 134, which may be wired or wireless communications links.The wireless communications system 100 may support operation on multiplecarriers (waveform signals of different frequencies). Multi-carriertransmitters can transmit modulated signals simultaneously on themultiple carriers. For example, each of communications links 125 may bea multi-carrier signal modulated according to the various radiotechnologies described above. Each modulated signal may be sent on adifferent carrier and may carry control information (e.g., referencesignals, control channels, etc.), overhead information, data, etc. Forexample, the multiple carriers can be with multiple cells (e.g., aprimary cell and one or more secondary cells, or a set of primary cellswith sets of one or more corresponding secondary cells, as describedbelow).

In some examples, at least a portion of the wireless communicationssystem 100 may be configured to operate on multiple hierarchical layersin which one or more of the UEs 115 and one or more of the access points105 may be configured to support transmissions on a hierarchical layerthat has a reduced latency with respect to another hierarchical layer.In some examples, a hybrid UE 115-a may communicate with access point105-a on both a first hierarchical layer that supports first layertransmissions using a first TTI (also referred to herein as “legacycommunications”) and a second hierarchical layer that supports secondlayer transmissions using a second TTI, which may be shorter than thefirst TTI (also referred to herein as “ULL communications”).

In other examples, a second layer UE 115-b may communicate with accesspoint 105-b on the second hierarchical layer only. Thus, hybrid UE 115-aand second layer UE 115-b may belong to a second class of UEs 115 thatmay communicate on the second hierarchical layer, while legacy UEs 115may belong to a first class of UEs 115 that may communicate on the firsthierarchical layer only. Access point 105-b and UE 115-b may communicateon the second hierarchical layer through transmissions of subframes ofthe second subframe type. Access point 105-b may transmit communicationsrelated to the first or second hierarchical layer only or may transmitcommunications for both the first and second hierarchical layers. Wherean access point 105-b supports both the first and second hierarchicallayers, communicating component 361 can be configured to prioritizecommunications received from the access point 105-b that relate to thefirst and second hierarchical layers, as described herein.

The access points 105 may wirelessly communicate with the UEs 115 viaone or more access point antennas. Each of the access points 105 sitesmay provide communication coverage for a respective coverage area 110.In some examples, access points 105 may be referred to as a basetransceiver station, a radio base station, a radio transceiver, a basicservice set (BSS), an extended service set (ESS), a NodeB, eNodeB, HomeNodeB, a Home eNodeB, or some other suitable terminology. The coveragearea 110 for a base station may be divided into sectors making up only aportion of the coverage area (not shown). The wireless communicationssystem 100 may include access points 105 of different types (e.g.,macro, micro, and/or pico base stations). The access points 105 may alsoutilize different radio technologies, such as cellular and/or WLAN radioaccess technologies (RAT). The access points 105 may be associated withthe same or different access networks or operator deployments. Thecoverage areas of different access points 105, including the coverageareas of the same or different types of access points 105, utilizing thesame or different radio technologies, and/or belonging to the same ordifferent access networks, may overlap.

In LTE/LTE-A and/or ULL LTE network communication systems, the termsevolved Node B (eNodeB or eNB) may be generally used to describe theaccess points 105. The wireless communications system 100 may be aHeterogeneous LTE/LTE-A/ULL LTE network in which different types ofaccess points provide coverage for various geographical regions. Forexample, each access point 105 may provide communication coverage for amacro cell, a pico cell, a femto cell, and/or other types of cell. Smallcells such as pico cells, femto cells, and/or other types of cells mayinclude low power nodes or LPNs. A macro cell may cover a relativelylarge geographic area (e.g., several kilometers in radius) and may allowunrestricted access by UEs 115 with service subscriptions with thenetwork provider. A small cell may cover a relatively smaller geographicarea and may allow unrestricted access by UEs 115 with servicesubscriptions with the network provider, for example, and in addition tounrestricted access, may also provide restricted access by UEs 115having an association with the small cell (e.g., UEs in a closedsubscriber group (CSG), UEs for users in the home, and the like). An eNBfor a macro cell may be referred to as a macro eNB. An eNB for a smallcell may be referred to as a small cell eNB. An eNB may support one ormultiple (e.g., two, three, four, and the like) cells.

The core network 130 may communicate with the eNBs or other accesspoints 105 via a backhaul links 132 (e.g., S1 interface, etc.). Theaccess points 105 may also communicate with one another, e.g., directlyor indirectly via backhaul links 134 (e.g., X2 interface, etc.) and/orvia backhaul links 132 (e.g., through core network 130). The wirelesscommunications system 100 may support synchronous or asynchronousoperation. For synchronous operation, the access points 105 may havesimilar frame timing, and transmissions from different access points 105may be approximately aligned in time. For asynchronous operation, theaccess points 105 may have different frame timing, and transmissionsfrom different access points 105 may not be aligned in time.Furthermore, transmissions in the first hierarchical layer and secondhierarchical layer may or may not be synchronized among access points105. The techniques described herein may be used for either synchronousor asynchronous operations.

The UEs 115 are dispersed throughout the wireless communications system100, and each UE 115 may be stationary or mobile. A UE 115 may also bereferred to by those skilled in the art as a mobile station, asubscriber station, a mobile unit, a subscriber unit, a wireless unit, aremote unit, a mobile device, a wireless device, a wirelesscommunications device, a remote device, a mobile subscriber station, anaccess terminal, a mobile terminal, a wireless terminal, a remoteterminal, a handset, a user agent, a mobile client, a client, or someother suitable terminology. A UE 115 may be a cellular phone, a personaldigital assistant (PDA), a wireless modem, a wireless communicationdevice, a handheld device, a tablet computer, a laptop computer, acordless phone, a wearable item such as a watch or glasses, a wirelesslocal loop (WLL) station, or the like. A UE 115 may be able tocommunicate with macro eNodeBs, small cell eNodeBs, relays, and thelike. A UE 115 may also be able to communicate over different accessnetworks, such as cellular or other WWAN access networks, or WLAN accessnetworks.

The communications links 125 shown in wireless communications system 100may include uplink (UL) transmissions from a UE 115 to an access point105, and/or downlink (DL) transmissions, from an access point 105 to aUE 115. The downlink transmissions may also be called forward linktransmissions while the uplink transmissions may also be called reverselink transmissions. The communications links 125 may carry transmissionsof each hierarchical layer which, in some examples, may be multiplexedin the communications links 125. The UEs 115 may be configured tocollaboratively communicate with multiple access points 105 through, forexample, Multiple Input Multiple Output (MIMO), carrier aggregation(CA), Coordinated Multi-Point (CoMP), multiple connectivity, or otherschemes. MIMO techniques use multiple antennas on the access points 105and/or multiple antennas on the UEs 115 to transmit multiple datastreams.

For example, carrier aggregation may utilize two or more componentcarriers on a same or different serving cell for data transmission. CoMPmay include techniques for coordination of transmission and reception bya number of access points 105 to improve overall transmission qualityfor UEs 115 as well as increasing network and spectrum utilization. Inmultiple connectivity, for example, UE 115 can be configured with atleast one primary cell (PCell) configured to support uplink and downlinkcommunications between UE 115 and an access point 105. It is to beappreciated that there can be a PCell for each of one or morecommunications links 125 between a UE 115 and a given access point 105.In addition, each of the communications links 125 can have one or moresecondary cells (SCell) that can support uplink and/or downlinkcommunications as well. In some examples, the PCell can be used tocommunicate at least a control channel, and the SCell can be used tocommunicate a data channel. The UE 115 may have multiple PCell linkswith multiple access points and/or multiple SCell links with multipleaccess points. In any case, in a multiple carrier configuration, the UE115 can establish CCs with each PCell and/or SCell.

As mentioned, in some examples access points 105 and UEs 115 may utilizecarrier aggregation to transmit on multiple carriers. In some examples,access points 105 and UEs 115 may concurrently transmit in a firsthierarchical layer, within a frame, one or more subframes each having afirst subframe type using two or more separate carriers. Each carriermay have a bandwidth of, for example, 20 MHz, although other bandwidthsmay be utilized. Hybrid UE 115-a, and/or second layer UE 115-b may, incertain examples, receive and/or transmit one or more subframes in asecond hierarchical layer utilizing a single carrier that has abandwidth greater than a bandwidth of one or more of the separatecarriers. For example, if four separate 20 MHz carriers are used in acarrier aggregation scheme in the first hierarchical layer, a single 80MHz carrier may be used in the second hierarchical layer. The 80 MHzcarrier may occupy a portion of the radio frequency spectrum that atleast partially overlaps the radio frequency spectrum used by one ormore of the four 20 MHz carriers. In some examples, scalable bandwidthfor the second hierarchical layer type may be combined techniques toprovide shorter RTTs such as described above, to provide furtherenhanced data rates.

Each of the different operating modes that may be employed by wirelesscommunications system 100 may operate according to frequency divisionduplexing (FDD) or time division duplexing (TDD). In some examples,different hierarchical layers may operate according to different TDD orFDD modes. For example, a first hierarchical layer may operate accordingto FDD while a second hierarchical layer may operate according to TDD.In some examples, OFDMA communications signals may be used in thecommunications links 125 for LTE downlink transmissions for eachhierarchical layer, while single carrier frequency division multipleaccess (SC-FDMA) communications signals may be used in thecommunications links 125 for LTE uplink transmissions in eachhierarchical layer. Additional details regarding implementation ofhierarchical layers in a system such as the wireless communicationssystem 100, as well as other features and functions related tocommunications in such systems, are provided below with reference to thefollowing figures.

FIG. 2 is a diagram illustrating an example of an access network 200 inan LTE or ULL LTE network architecture. In this example, the accessnetwork 200 is divided into a number of cellular regions (cells) 202.One or more small cell eNBs 208 can be provided that may be of a lowerpower class and may have cellular regions 210 that overlap with one ormore of the cells 202. The small cell eNBs 208 may be or may provide afemto cell (e.g., home eNB (HeNB)), pico cell, micro cell, or remoteradio head (RRH). The macro eNBs 204 are each assigned to a respectivecell 202 and are configured to provide an access point to the corenetwork 130 for all the UEs 206 in the cells 202. In an aspect, eNBs 204(or small cell eNBs 208) may include scheduling component 302 configuredto activate/deactivate one or more CCs or allocate resources forcommunicating using legacy or ULL communications to one or more UEs 206,as described further herein. Similarly, one or more of UEs 206 mayinclude a communicating component 361 configured to receive informationrelated to activating/deactivating a CC and/or resources forcommunicating using legacy or ULL communications with the eNBs 204and/or 208. There is no centralized controller in this example of anaccess network 200, but a centralized controller may be used inalternative configurations. The eNBs 204 are responsible for all radiorelated functions including radio bearer control, admission control,mobility control, scheduling, security, and connectivity to one or morecomponents of core network 130.

The modulation and multiple access scheme employed by the access network200 may vary depending on the particular telecommunications standardbeing deployed. In LTE or ULL LTE applications, OFDM may be used on theDL and SC-FDMA may be used on the UL to support both frequency divisionduplexing (FDD) and time division duplexing (TDD). As those skilled inthe art will readily appreciate from the detailed description to follow,the various concepts presented herein are well suited for LTEapplications. However, these concepts may be readily extended to othertelecommunication standards employing other modulation and multipleaccess techniques. By way of example, these concepts may be extended toEvolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DOand UMB are air interface standards promulgated by the 3rd GenerationPartnership Project 2 (3GPP2) as part of the CDMA2000 family ofstandards and employs CDMA to provide broadband Internet access tomobile stations. These concepts may also be extended to UniversalTerrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) andother variants of CDMA, such as TD-SCDMA; Global System for MobileCommunications (GSM) employing TDMA; and Evolved UTRA (E-UTRA), IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDMemploying OFDMA. UTRA, E-UTRA, UMTS, LTE and GSM are described indocuments from the 3GPP organization. CDMA2000 and UMB are described indocuments from the 3GPP2 organization. The actual wireless communicationstandard and the multiple access technology employed will depend on thespecific application and the overall design constraints imposed on thesystem.

The eNBs 204 may have multiple antennas supporting MIMO technology. Theuse of MIMO technology enables the eNBs 204 to exploit the spatialdomain to support spatial multiplexing, beamforming, and transmitdiversity. Spatial multiplexing may be used to transmit differentstreams of data simultaneously on the same frequency. The data steamsmay be transmitted to a single UE 206 to increase the data rate or tomultiple UEs 206 to increase the overall system capacity. This isachieved by spatially precoding each data stream (i.e., applying ascaling of an amplitude and a phase) and then transmitting eachspatially precoded stream through multiple transmit antennas on the DL.The spatially precoded data streams arrive at the UE(s) 206 withdifferent spatial signatures, which enables each of the UE(s) 206 torecover the one or more data streams destined for that UE 206. On theUL, each UE 206 transmits a spatially precoded data stream, whichenables the eNBs 204 to identify the source of each spatially precodeddata stream.

Spatial multiplexing is generally used when channel conditions are good.When channel conditions are less favorable, beamforming may be used tofocus the transmission energy in one or more directions. This may beachieved by spatially precoding the data for transmission throughmultiple antennas. To achieve good coverage at the edges of the cell, asingle stream beamforming transmission may be used in combination withtransmit diversity.

In the detailed description that follows, various aspects of an accessnetwork will be described with reference to a MIMO system supportingOFDM on the DL. OFDM is a spread-spectrum technique that modulates dataover a number of subcarriers within an OFDM symbol. The subcarriers arespaced apart at precise frequencies. The spacing provides“orthogonality” that enables a receiver to recover the data from thesubcarriers. In the time domain, a guard interval (e.g., cyclic prefix)may be added to each OFDM symbol to combat inter-OFDM-symbolinterference. The UL may use SC-FDMA in the form of a DFT-spread OFDMsignal to compensate for high peak-to-average power ratio (PAPR).

FIG. 3 is a block diagram of an eNB 310 in communication with a UE 350in an access network. In the DL, upper layer packets from the corenetwork are provided to a controller/processor 375. Thecontroller/processor 375 implements the functionality of the L2 layer.In the DL, the controller/processor 375 provides header compression,ciphering, packet segmentation and reordering, multiplexing betweenlogical and transport channels, and radio resource allocations to the UE350 based on various priority metrics. The controller/processor 375 isalso responsible for HARQ operations, retransmission of lost packets,and signaling to the UE 350.

The transmit (TX) processor 316 implements various signal processingfunctions for the L1 layer (i.e., physical layer). The signal processingfunctions includes coding and interleaving to facilitate forward errorcorrection (FEC) at the UE 350 and mapping to signal constellationsbased on various modulation schemes (e.g., binary phase-shift keying(BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying(M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded andmodulated symbols are then split into parallel streams. Each stream isthen mapped to an OFDM subcarrier, multiplexed with a reference signal(e.g., pilot) in the time and/or frequency domain, and then combinedtogether using an Inverse Fast Fourier Transform (IFFT) to produce aphysical channel carrying a time domain OFDM symbol stream. The OFDMstream is spatially precoded to produce multiple spatial streams.Channel estimates from a channel estimator 374 may be used to determinethe coding and modulation scheme, as well as for spatial processing. Thechannel estimate may be derived from a reference signal and/or channelcondition feedback transmitted by the UE 350. Each spatial stream isthen provided to a different antenna 320 via a separate transmitter318TX. Each transmitter 318TX modulates an RF carrier with a respectivespatial stream for transmission. In addition, eNB 310 may includescheduling component 302 configured to activate/deactivate one or moreCCs or allocate resources for communicating using legacy or ULLcommunications to one or more UEs 350, as described further herein.Though scheduling component 302 is shown as coupled tocontroller/processor 375, it is to be appreciated that schedulingcomponent 302 can also be coupled to other processors (e.g., RXprocessor 370, TX processor 316, etc.) and/or implemented by the one ormore processors 316, 370, 375 to perform actions described herein

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The RX processor 356 implements various signalprocessing functions of the L1 layer. The RX processor 356 performsspatial processing on the information to recover any spatial streamsdestined for the UE 350. If multiple spatial streams are destined forthe UE 350, they may be combined by the RX processor 356 into a singleOFDM symbol stream. The RX processor 356 then converts the OFDM symbolstream from the time-domain to the frequency domain using a Fast FourierTransform (FFT). The frequency domain signal comprises a separate OFDMsymbol stream for each subcarrier of the OFDM signal. The symbols oneach subcarrier, and the reference signal, is recovered and demodulatedby determining the most likely signal constellation points transmittedby the eNB 310. These soft decisions may be based on channel estimatescomputed by the channel estimator 358. The soft decisions are thendecoded and deinterleaved to recover the data and control signals thatwere originally transmitted by the eNB 310 on the physical channel. Thedata and control signals are then provided to the controller/processor359.

The controller/processor 359 implements the L2 layer. Thecontroller/processor can be associated with a memory 360 that storesprogram codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the core network. The upper layerpackets are then provided to a data sink 362, which represents all theprotocol layers above the L2 layer. Various control signals may also beprovided to the data sink 362 for L3 processing. Thecontroller/processor 359 is also responsible for error detection usingan acknowledgement (ACK) and/or negative acknowledgement (NACK) protocolto support HARQ operations. In addition, UE 350 may include acommunicating component 361 configured to receive information related toactivating/deactivating a CC and/or resources for communicating usinglegacy or ULL communications with the eNB 310. Though communicatingcomponent 361 is shown as coupled to controller/processor 359, it is tobe appreciated that communicating component 361 can also be coupled toother processors (e.g., RX processor 356, TX processor 368, etc.) and/orimplemented by the one or more processors 356, 359, 368 to performactions described herein.

In the UL, a data source 367 is used to provide upper layer packets tothe controller/processor 359. The data source 367 represents allprotocol layers above the L2 layer. Similar to the functionalitydescribed in connection with the DL transmission by the eNB 310, thecontroller/processor 359 implements the L2 layer for the user plane andthe control plane by providing header compression, ciphering, packetsegmentation and reordering, and multiplexing between logical andtransport channels based on radio resource allocations by the eNB 310.The controller/processor 359 is also responsible for HARQ operations,retransmission of lost packets, and signaling to the eNB 310.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the eNB 310 may be used by the TXprocessor 368 to select the appropriate coding and modulation schemes,and to facilitate spatial processing. The spatial streams generated bythe TX processor 368 are provided to different antenna 352 via separatetransmitters 354TX. Each transmitter 354TX modulates an RF carrier witha respective spatial stream for transmission.

The UL transmission is processed at the eNB 310 in a manner similar tothat described in connection with the receiver function at the UE 350.Each receiver 318RX receives a signal through its respective antenna320. Each receiver 318RX recovers information modulated onto an RFcarrier and provides the information to a RX processor 370. The RXprocessor 370 may implement the L1 layer.

The controller/processor 375 implements the L2 layer. Thecontroller/processor 375 can be associated with a memory 376 that storesprogram codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the UE 350. Upper layer packets fromthe controller/processor 375 may be provided to the core network. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

FIG. 4 is a diagram illustrating non-limiting examples of a ULLtimelines 400, 402, with time extending from left to right in thefigure, for managing ULL communications in a wireless communicationsystem. In this example, timelines 400, 402 include ULL frames of symbolduration in each symbol of a subframe. Timelines 400, 402 both depictsymbols representing a TTI for ULL physical downlink control channel(uPDCCH) and/or ULL physical downlink shared channel (uPDSCH) andsymbols representing a TTI including ULL physical uplink control channel(uPUCCH) and/or ULL physical uplink shared channel (uPUSCH). Intimelines 400, 14 symbols are shown within a given subframe (e.g., fornormal CP), and in timelines 402, 12 symbols are shown within a givensubframe (e.g., for extended CP). In either case, lower latency isachieved in ULL by utilizing symbol-based TTIs. It is to be appreciated,in other examples, that a TTI may be two or more symbols, a slot of asubframe (where a subframe includes two slots), etc. In addition, HARQprocess response time can be 3 symbols (or 4 symbols, 3 dual-symbols, 3slots, etc.). In the depicted example, uPDCCH/uPDSCH is sent in symbol0, and HARQ is processed and is sent in symbol 4, etc. in the subframe.

Referring to FIGS. 5-7, aspects are depicted with reference to one ormore components and one or more methods that may perform the actions orfunctions described herein. In an aspect, the term “component” as usedherein may be one of the parts that make up a system, may be hardware orsoftware or some combination thereof, and may be divided into othercomponents. Although the operations described below in FIGS. 6 and 7 arepresented in a particular order and/or as being performed by an examplecomponent, it should be understood that the ordering of the actions andthe components performing the actions may be varied, depending on theimplementation. Moreover, it should be understood that the followingactions or functions may be performed by a specially-programmedprocessor, a processor executing specially-programmed software orcomputer-readable media, or by any other combination of a hardwarecomponent and/or a software component capable of performing thedescribed actions or functions.

FIG. 5 illustrates an example system 500 for allocating resources forlegacy and ULL wireless communications. System 500 includes a UE 502that communicates with an eNB 504 to access a wireless network, examplesof which are described in FIGS. 1-3 (e.g., access points 105, eNB 204,208, eNB 310, UEs 115, 206, 350, etc.), above. In an aspect, eNB 504 andUE 502 can communicate over a plurality of CCs 508, 509 (and/oradditional CCs) using carrier aggregation. For each CC 508, 509, forexample, eNB 504 and UE 502 may have established one or more downlinkchannels over which to communicate downlink signals, which can betransmitted by eNB 504 (e.g., via transceiver 556) and received by UE502 (e.g., via transceiver 506) for communicating control and/or datamessages (e.g., in signaling) from the eNB 504 to the UE 502 overconfigured communication resources. Moreover, for example, eNB 504 andUE 502 may have established one or more uplink channels over which tocommunicate via uplink signals for each CC 508, 509, which can betransmitted by UE 502 (e.g., via transceiver 506) and received by eNB504 (e.g., via transceiver 556) for communicating control and/or datamessages (e.g., in signaling) from the UE 502 to the eNB 504 overconfigured communication resources. In another example, UE 502 maycommunicate with eNB 504 over one CC 508 and another eNB (or anothercell provided by eNB 504) over another CC 509, may communicate with botheNBs (or cells) over multiple CCs, etc., though not shown in thisFigure. Moreover, for example, UE 502 and/or eNB 504 can configure oneCC 508 as a PCell CC and one or more other CCs 509 as an SCell CC incarrier aggregation and/or multiple connectivity. In addition, in anexample, each CC 508 and/or 509 can be a set of CCs including a separateuplink CC and downlink CC.

In an aspect, UE 502 may include one or more processors 503 and/or amemory 505 that may be communicatively coupled, e.g., via one or morebuses 507, and may operate in conjunction with or otherwise implement acommunicating component 361 for receiving resource grants from eNB 504and communicating over the resources, which may be based on a ULLtimeline (e.g., a timeline having a TTI that is less than a subframe induration, such as the timelines 400, 402 in FIG. 4), a legacy timeline(e.g., a timeline with a 1 ms subframe TTI), etc. For example, thevarious operations related to communicating component 361 may beimplemented or otherwise executed by one or more processors 503 and, inan aspect, can be executed by a single processor, while in otheraspects, different ones of the operations may be executed by acombination of two or more different processors. For example, in anaspect, the one or more processors 503 may include any one or anycombination of a modem processor, or a baseband processor, or a digitalsignal processor, or an application specific integrated circuit (ASIC),or a transmit processor, receive processor, or a transceiver processorassociated with transceiver 506. Further, for example, the memory 505may be a non-transitory computer-readable medium that includes, but isnot limited to, random access memory (RAM), read only memory (ROM),programmable ROM (PROM), erasable PROM (EPROM), electrically erasablePROM (EEPROM), a magnetic storage device (e.g., hard disk, floppy disk,magnetic strip), an optical disk (e.g., compact disk (CD), digitalversatile disk (DVD)), a smart card, a flash memory device (e.g., card,stick, key drive), a register, a removable disk, and any other suitablemedium for storing software and/or computer-readable code orinstructions that may be accessed and read by a computer or one or moreprocessors 503. Moreover, memory 505 or computer-readable storage mediummay be resident in the one or more processors 503, external to the oneor more processors 503, distributed across multiple entities includingthe one or more processors 503, etc.

In particular, the one or more processors 503 and/or memory 505 mayexecute actions or operations defined by communicating component 361 orits subcomponents. For instance, the one or more processors 503 and/ormemory 505 may execute actions or operations defined by a configurationreceiving component 510 for obtaining a configuration for communicatingover a plurality of CCs with one or more cells (e.g., with one or moreeNBs 504) using carrier aggregation, multiple connectivity, etc. In anaspect, for example, configuration receiving component 510 may includehardware (e.g., one or more processor modules of the one or moreprocessors 503) and/or computer-readable code or instructions stored inmemory 505 and executable by at least one of the one or more processors503 to perform the specially configured configuration receivingoperations described herein. Further, for instance, the one or moreprocessors 503 and/or memory 505 may execute actions or operationsdefined by an optional communication activating/deactivating component512 for activating and/or deactivating legacy and/or ULL communicationswith eNB 504. In an aspect, for example, communicationactivating/deactivating component 512 may include hardware (e.g., one ormore processor modules of the one or more processors 503) and/orcomputer-readable code or instructions stored in memory 505 andexecutable by at least one of the one or more processors 503 to performthe specially configured activating/deactivating operations describedherein. Further, for instance, the one or more processors 503 and/ormemory 505 may execute actions or operations defined by an optionallatency determining component 514 for determining a latency foractivating/deactivating the communications. In an aspect, for example,latency determining component 514 may include hardware (e.g., one ormore processor modules of the one or more processors 503) and/orcomputer-readable code or instructions stored in memory 505 andexecutable by at least one of the one or more processors 503 to performthe specially configured latency determining operations describedherein.

Similarly, in an aspect, eNB 504 may include one or more processors 553and/or a memory 555 that may be communicatively coupled, e.g., via oneor more buses 557, and may operate in conjunction with or otherwiseimplement a scheduling component 302 for generating the resource grantsfor UE 502 and/or other UEs according to the resources, which may bebased on a ULL timeline (e.g., a timeline having a TTI that is less thana subframe in duration, such as the timelines 400, 402 in FIG. 4), alegacy timeline (e.g., a timeline with a 1 ms subframe TTI), etc. Forexample, the various functions related to scheduling component 302 maybe implemented or otherwise executed by one or more processors 553 and,in an aspect, can be executed by a single processor, while in otheraspects, different ones of the functions may be executed by acombination of two or more different processors, as described above. Itis to be appreciated, in one example, that the one or more processors553 and/or memory 555 may be configured as described in examples abovewith respect to the one or more processors 503 and/or memory 505 of UE502.

In an example, the one or more processors 553 and/or memory 555 mayexecute actions or operations defined by scheduling component 302 or itssubcomponents. For instance, the one or more processors 553 and/ormemory 555 may execute actions or operations defined by a configuringcomponent 520 for configuring legacy and/or ULL communications for UE502 over at least one CC, where the UE 502 can otherwise be configuredover multiple CCs with eNB 504 or other eNBs/cells in carrieraggregation or multiple connectivity. In an aspect, for example,configuring component 520 may include hardware (e.g., one or moreprocessor modules of the one or more processors 553) and/orcomputer-readable code or instructions stored in memory 555 andexecutable by at least one of the one or more processors 553 to performthe specially configured communication configuring operations describedherein. Further, for instance, the one or more processors 553 and/ormemory 555 may execute actions or operations defined by an optionalcommunication activating/deactivating component 522 foractivating/deactivating legacy and/or ULL communications with the UE 502over the at least one CC. In an aspect, for example, communicationactivating/deactivating component 522 may include hardware (e.g., one ormore processor modules of the one or more processors 553) and/orcomputer-readable code or instructions stored in memory 555 andexecutable by at least one of the one or more processors 553 to performthe specially configured activating/deactivating operations describedherein.

It is to be appreciated that transceivers 506, 556 may be configured totransmit and receive wireless signals through one or more antennas, anRF front end, one or more transmitters, and one or more receivers. In anaspect, transceivers 506, 556 may be tuned to operate at specifiedfrequencies such that UE 502 and/or eNB 504 can communicate at a certainfrequency. In an aspect, the one or more processors 503 may configuretransceiver 506 and/or one or more processors 553 may configuretransceiver 556 to operate at a specified frequency and power levelbased on a configuration, a communication protocol, etc. to communicateuplink signals and/or downlink signals over related uplink or downlinkcommunication channels over the one or more CCs.

In an aspect, transceivers 506, 556 can operate in multiple bands (e.g.,using a multiband-multimode modem, not shown) such to process digitaldata sent and received using transceivers 506, 556. In an aspect,transceivers 506, 556 can be multiband and be configured to supportmultiple frequency bands for a specific communications protocol. In anaspect, transceivers 506, 556 can be configured to support multipleoperating networks and communications protocols. Thus, for example,transceivers 506, 556 may enable transmission and/or reception ofsignals based on a specified modem configuration.

FIG. 6 illustrates an example method 600 for managing (e.g., by a UE502) legacy and/or ULL communications with one or more cells. At Block602, the UE 502 may receive a configuration for aggregating a set ofCCs. In such an aspect, set of CCs may include at least a primary cellCC and a secondary cell CC. In an aspect, configuration receivingcomponent 510 (FIG. 5), e.g., in conjunction with processor(s) 503,memory 505, and/or transceiver 506, can receive the configuration foraggregating a set of CCs. In such an aspect, the set of CCs may includeat least a primary cell CC and a secondary cell CC. In one example,configuration receiving component 510 can receive the configuration forthe set of CCs from eNB 504 and/or may receive the configuration for oneor a subset of the set of CCs configured for UE 502 from eNB 504. Theconfiguration may specify a frequency band for the CCs, cell informationassigned to the CCs, a communication technology for the CCs (e.g.,legacy and/or ULL), resources over which to communicate using the CCs,and/or the like. In one example, configuration receiving component 510can receive the configuration from the eNB 504, which can specifyutilization of legacy and/or ULL communications over the CC where thelegacy and/or ULL communications can relate to one or more of uplink ordownlink communications over the CC. In an example, the configurationcan relate to a PCell CC and one or more SCell CCs in carrieraggregation (e.g., with cells of eNB 504 and/or other eNBs) and/ormultiple connectivity (e.g., with multiple PCell CCs and correspondingSCell CC(s)). In an example, the PCell CC can include a common searchspace over which the UE 502 can search for resource grants on the PCellCC and/or one or more SCell CCs.

At Block 604, the UE 502 may communicate, based on the receivedconfiguration, with at least the primary cell for legacy communications.In an aspect, communicating component 361, e.g., in conjunction withprocessor(s) 503, memory 505, and/or transceiver 506, can communicate,based on the received configuration, with at least the primary cell forlegacy communications. As described, the legacy communications can bebased on a first TTI of a first duration that is more than a secondduration of a second TTI upon which ULL communications are based. In anexample, communicating component 361 can communicate with eNB 504 over aprimary cell CC (e.g., CC 508). As described, for example, theconfiguration can specify one or more parameters related tocommunicating over the primary cell (e.g., frequency band, cellinformation, communication technology, resources for uplink/downlinkcontrol and/or data communications, etc.). Thus, communicating component361 can utilize the one or more parameters to communicate with the eNB504 using the primary cell (e.g., over CC 508) using at least legacycommunications (e.g., legacy LTE). In one example, UE 502 may receivethe configuration over the primary cell communications with eNB 504(e.g., over CC 508).

At Block 606, the UE 502 may communicate, based on the receivedconfiguration, with at least one of the primary cell or the secondarycell for ULL communications. In an aspect, communicating component 361,e.g., in conjunction with processor(s) 503, memory 505, and/ortransceiver 506, can communicate, based on the received configuration,with at least one of the primary cell or the secondary cell for ULLcommunications. This can include communicating with eNB 504 over aprimary cell CC and secondary cell CC (e.g., CCs 508, 509,respectively), and/or can include communicating with eNB 504 over aprimary cell CC and another eNB (not shown) that provides one of thecells over a secondary cell CC. As described, for example, theconfiguration can specify one or more parameters related tocommunicating over the primary and secondary cells (e.g., frequencyband, cell information, communication technology, resources foruplink/downlink control and/or data communications, etc.). Thus,communicating component 361 can utilize the one or more parameters tocommunicate with the eNB 504 using the primary cell (e.g., over CC 508)and/or the secondary cell (e.g., over CC 509) using at least ULLcommunications (e.g., ULL LTE). For example, ULL LTE communications canbe based on a TTI that is 1 symbol, 2 symbols, 1 slot, etc. durations,where legacy LTE may be based on a TTI that is 1 subframe in duration.Accordingly, communicating component 361 can separately manage legacyand/or ULL communications over a plurality of CCs.

In one example, communicating component 361 can communicate over theprimary cell (and/or a second primary cell carrying PUCCH/uPUCCH,referred to herein as a pScell) using ULL and legacy LTE (which mayinclude monitoring for communications over the primary cell CC 508 usingULL and legacy LTE) while communicating with the secondary cell using atleast ULL LTE (which may include monitoring for communications over thesecondary cell CC 509 using at least ULL LTE). In another example,communicating component 361 can communicate over the secondary cellusing legacy LTE (which may include monitoring for communications overthe secondary cell CC 509 using at least legacy LTE). Thus, for example,communicating component 361 may communicate with a PCell and an SCell(e.g., of eNB 504 and/or one or more other eNBs), or related PCell CC orSCell CC, based on one or more of the following communication typeconfigurations: (1) PCell using a legacy technology and SCell using aULL (and legacy) technology; (2) PCell using a ULL (and legacy)technology and SCell using a legacy technology; or (3) PCell using a ULL(and legacy) technology and SCell using a ULL (and legacy) technology.It is to be appreciated that additional configurations are possible formore than 2 CCs and/or in multiple connectivity. In an example, thoughcommunicating component 361 can monitor, based on the receivedconfiguration, legacy LTE over the SCell for communications, the SCellmay provide ULL communications to other UEs over other CCs. Similarly,though communicating component 361 can monitor, based on the receivedconfiguration, ULL LTE over the SCell for communications, the SCell mayprovide legacy communications to other UEs over other CCs.

In addition, the communication type configuration may be based in parton subframe/frame configurations over the CCs (e.g., since different CCscan have different uplink/downlink subframe configurations and/ordifferent frame structures, such as FDD or TDD). In addition, in anexample, communicating component 361 may communicate with the PCelland/or SCell using a legacy technology on an uplink portion of a CC 508,509 and a ULL (and legacy) technology on a downlink portion of the CC508, 509, and/or vice versa.

In an example, at Block 608, the UE 502 may optionally receive anactivation command for activating legacy communications with the primarycell or the secondary cell and/or a deactivation command fordeactivating ULL communications with the primary cell or the secondarycell. In an aspect, communication activating/deactivating component 512,e.g., in conjunction with processor(s) 503, memory 505, and/ortransceiver 506, may receive the activation command for activatinglegacy communications with the primary cell or the secondary cell and/ora deactivation command for deactivating ULL communications with theprimary cell or the secondary cell (e.g., from eNB 504, as describedfurther herein). For example, communicating component 361 may receivethe activation command and/or the deactivation command in legacy and/orULL resources over the primary cell (e.g., primary cell CC 508),secondary cell (e.g., secondary cell CC 509), and/or other CCs. In oneexample, communication activating/deactivating component 512 can requestactivation/deactivation of legacy and/or ULL communications in thesecondary cell from eNB 504. Communication activating/deactivatingcomponent 512 can accordingly activate legacy communications and/ordeactivate ULL communications over the secondary cell CC 509 (e.g., overa corresponding uplink and/or downlink CC). This may include refrainingfrom monitoring for ULL communications (e.g., at the TTI of the ULLcommunications) over the secondary cell CC 509, refraining fromtransmitting ULL communications over the secondary cell CC 509, etc. Inthis regard, latency for establishing legacy communications using ULLcommunications over the CC can be less than establishing the CCaltogether in the secondary cell.

In addition, in an example, where ULL communications are deactivated,communication activating/deactivating component 512 may receive acommand to activate the ULL communications over the secondary cell CC509 from the eNB 504 or another eNB related to the secondary cell CC 509(and/or a command to deactivate the legacy communications in thesecondary cell). Communication activating/deactivating component 512 canaccordingly activate ULL communications and/or deactivate legacycommunications in the secondary cell CC 509 based on the command(s). Inthis regard, latency for establishing ULL communications using legacycommunications over the CC can be less than establishing the CCaltogether in the secondary cell. Moreover, the activation/deactivationcommands in any case may apply to downlink communications (e.g. over adownlink CC portion of the secondary cell CC 509), uplink communications(e.g., over an uplink CC portion of the secondary cell CC 509), both,etc.

As described, for example, ULL or legacy communications can be activatedand/or deactivated for one of downlink or uplink communications, or forboth downlink and uplink communications in the secondary cell. When ULLor legacy communications are activated and/or deactivated for downlinkor uplink, the ULL or legacy configuration can also be subframedependent (e.g., legacy only communications activated in some subframeswhile legacy and ULL are activated in other subframes depending onwhether the subframes are configured for downlink and/or uplinkcommunications).

At Block 610, the UE 502 may optionally determine a latency foractivating legacy communications with the primary cell or the secondarycell (e.g., over the corresponding CC 509) or deactivating ULLcommunications with the primary cell or the secondary cell. In anaspect, latency determining component 514, e.g., in conjunction withprocessor(s) 503 and/or memory 505, can determine the latency foractivating legacy communications with the primary cell or the secondarycell or deactivating ULL communications with the primary cell or thesecondary cell. For example, where the UE 502 is not communicating withthe secondary cell, latency determining component 514 can determine alonger latency for activating legacy communications than where the UE502 is communicating with the secondary cell before activating thelegacy communications. In another example, where the UE 502 is notcommunicating with the secondary cell after deactivating the ULLcommunications, latency determining component 514 can determine a longerlatency for deactivating legacy communications than where the UE 502continues communicating with the secondary cell (e.g., using legacycommunications) after deactivating the ULL communications. It is to beappreciated that latencies can be similarly determined for reactivationof ULL communications and/or deactivation of legacy communications.

In yet another example, latency determining component 514 can determinethe latency for activating or deactivating legacy or ULL communicationson the secondary cell (e.g., over the corresponding CC 509) based onwhether the activation or deactivation command is for legacycommunications (e.g., based on the first TTI) or ULL communications(e.g., based on the second TTI). For example, where theactivation/deactivation command is for ULL communications, latencydetermining component 514 can determine a shorter latency than when theactivation/deactivation command is for legacy communications. In anotherexample, latency determining component 514 may determine the latencybased on whether the UE 502 communicates with the secondary cell usingat least one TTI before and after the activating and/or deactivating. Inany case, communicating component 361 can utilize the latency indetermining when (e.g., in what TTI) to communicate (e.g., transmitand/or receive) over activated resources and/or refrain fromcommunicating over deactivated resources.

FIG. 7 illustrates an example method 700 for communicating (e.g., by aneNB 504) with a UE using legacy and/or ULL communications. At Block 702,the eNB may configure a UE for communicating over at least one CC of aplurality of CCs configured for the UE. In an aspect, configuringcomponent 520 (FIG. 5), e.g., in conjunction with processor(s) 553,memory 555, and/or transceiver 556, can configure the UE 502 forcommunicating over at least one CC of a plurality of CCs configured forthe UE 502. For example, configuring component 520 can specifyinformation for communicating with a primary cell over CC 508 and/orwith a secondary cell (e.g., associated with the eNB 504 or another eNB)over CC 509 in carrier aggregation and/or in multiple connectivity. Asdescribed, for example, the information can include frequency band, cellinformation, communication technology, resources for uplink/downlinkcontrol and/or data communications, or other parameters.

At Block 704, the eNB 504 may communicate with the UE over at least oneCC using ULL communications. In an aspect, scheduling component 302,e.g., in conjunction with processor(s) 553, memory 555, and/ortransceiver 556, can communicate with the UE 502 over at least one CC508 and/or 509 using ULL communications, as described above (e.g., basedon a ULL timeline). This can be based at least in part on theconfiguration sent to the UE 502.

At Block 706, the eNB 504 may activate legacy communications with the UEover the at least one CC. In an aspect, communicationactivating/deactivating component 522, e.g., in conjunction withprocessor(s) 553, memory 555, and/or transceiver 556, can activatelegacy communications with the UE 502 over the at least one CC 508, 509.For example, in activating the legacy communications at Block 706, theeNB 504 may optionally, at Block 708, send a command to the UE toactivate the legacy communications. In an aspect, communicationactivating/deactivating component 522, e.g., in conjunction withprocessor(s) 553, memory 555, and/or transceiver 556, may send thecommand to the UE 502 to activate the legacy communications. Forexample, communication activating/deactivating component 522 cantransmit the command to the UE 502 using ULL communications therewith(e.g., over CC 508 and/or 509).

At Block 710, the eNB 504 may optionally deactivate ULL communicationswith the UE over the at least one CC based on activating the legacycommunications. In an aspect, communication activating/deactivatingcomponent 522, e.g., in conjunction with processor(s) 553, memory 555,and/or transceiver 556, can deactivate the ULL communications with theUE 502 over at least one CC 508, 509 based on activating the legacycommunications. For example, in deactivating the ULL communications atBlock 710, the eNB 504 may optionally, at Block 712, send a command tothe UE to deactivate the ULL communications. In an aspect, communicationactivating/deactivating component 522, e.g., in conjunction withprocessor(s) 553, memory 555, and/or transceiver 556, can transmit thecommand to the UE 502 using the ULL or legacy communications (e.g., overCC 508 and/or 509). It is to be appreciated that eNB 504 can maintainULL communications with other UEs when deactivating ULL communicationswith UE 502.

In addition, communication activating/deactivating component 522 cansimilarly activate ULL and/or deactivate legacy communications in thesecondary cell for UE 502 as well, which may include sending relatedcommands to the UE 502. In any case, in an example, communicationactivating/deactivating component 522 may determine toactivate/deactivate ULL and/or legacy communications based on a requestfrom the UE 502, based on a buffer status report from the UE 502, etc.For example, where the eNB 504 receives a buffer status report from theUE 502 indicating a buffer status below a threshold capacity where ULLcommunications are active, communication activating/deactivatingcomponent 522 may deactivate ULL communications and/or activate legacycommunications over the secondary cell CC 509 for UE 502 (e.g., and/ormay deactivate the secondary cell CC 509 altogether). Similarly, forexample, where the eNB 504 receives a buffer status report from the UE502 indicating a buffer status achieves a threshold capacity wherelegacy communications are active, communication activating/deactivatingcomponent 522 may activate ULL communications and/or deactivate legacycommunications over the secondary cell CC 509 for UE 502. In addition,in an example, communication activating/deactivating component 522 canactivate/deactivate legacy and/or ULL communications based on a type oftraffic to be communicated over the secondary cell CC 509 (e.g.,activate ULL communications for media traffic, activate legacycommunications for traffic having lower bandwidth requirements, etc.).

Accordingly, the eNB 504 can configure ULL and/or legacy communicationsover a given CC 508, 509 with UE 502 in carrier aggregation. It is to beappreciated that one CC (e.g., primary cell CC 508) can utilize ULL andlegacy communications while another CC (e.g., secondary cell CC 509) canutilize ULL or legacy communications. The eNB 504 can accordinglyactivate and/or deactivate ULL or legacy communications as describedherein. It is also to be appreciated that a CC may be configured ULLonly for a direction (e.g., downlink ULL) while relying on a differentCC for ULL of a different direction (e.g., uplink ULL). For example, aCC that a UE monitors for a common search space, e.g., the primary cellCC 508, a primary second CC (pScell) that may carry control channels,etc., may be restricted such that ULL is to be configured for both links(downlink and uplink) if configured. It is also to be appreciated thatthe primary cell CC configured for legacy communication can berestricted to be the same as the primary cell CC for ULL communication.Alternatively, the primary cell CC for legacy communication and theprimary cell CC for ULL communication can be separately managed andconfigured, as described herein. As an example, a UE may be configuredwith 3 CCs: CC1, CC2, and CC3. CC1 may be configured as the primary cellCC for legacy communication, while CC2 may be configured as the primarycell CC for ULL communication. CC3 may be configured as a secondary cellCC. Thus, in an example as described herein, communicationactivating/deactivating component 512 may receive instructions over CC1for activating/deactivating ULL communications on CC2, and/or viceversa. In any case, as described, one or more eNBs may provide theconfiguration to the UE (e.g., as described with respect to Block 602and/or 702 above).

In addition, cross-carrier scheduling may be enabled for ULLcommunication. That is, a ULL control channel can be transmitted over aCC (e.g., primary cell CC 508 by eNB 504) for scheduling ULLcommunication (downlink or uplink) on a different CC (e.g., secondarycell CC 509). It is also possible that a ULL communication (downlink oruplink) may be scheduled for a CC by a control channel associated withlegacy communication on the CC or another CC (e.g., by eNB 504).Similarly, it is also possible that a legacy communication (downlink oruplink) may be scheduled by a control channel associated with ULLcommunication.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Further, somesteps may be combined or omitted. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. All structural andfunctional equivalents to the elements of the various aspects describedherein that are known or later come to be known to those of ordinaryskill in the art are expressly incorporated herein by reference and areintended to be encompassed by the claims. Moreover, nothing disclosedherein is intended to be dedicated to the public regardless of whethersuch disclosure is explicitly recited in the claims. No claim element isto be construed as a means plus function unless the element is expresslyrecited using the phrase “means for.”

What is claimed is:
 1. A method of managing ultra low latency (ULL)communications over a plurality of component carriers (CC), comprising:receiving a configuration for aggregating a set of CCs, wherein the setof CCs includes at least a primary cell and a secondary cell;communicating, based on the received configuration, with at least theprimary cell for legacy communications, wherein the legacycommunications are based on a first transmission time interval (TTI)having a first duration; and communicating, based on the receivedconfiguration, with at least one of the primary cell or the secondarycell for ULL communications, wherein the ULL communications are based ona second TTI having a second duration that is less than the firstduration.
 2. The method of claim 1, further comprising: communicating,based on the received configuration, with the secondary cell for legacycommunications.
 3. The method of claim 1, wherein the receiving furthercomprises: receiving an activation command for the at least one of theprimary cell or the secondary cell for activating legacy communicationswith the at least one of the primary cell or the secondary cell.
 4. Themethod of claim 1, further comprising receiving a deactivation commandfor ULL communications with the at least one of the primary cell or thesecondary cell.
 5. The method of claim 4, further comprising receivingan activation command for activating legacy communications with thesecondary cell, along with deactivating ULL communications with thesecondary cell.
 6. The method of claim 1, further comprising determininga latency for activating or deactivating legacy or ULL communicationswith the at least one of the primary cell or the secondary cell, wherethe latency is a function of at least one of: whether the activating orthe deactivating is for communications based on the first TTI or thesecond TTI, or whether the UE communicates with a cell using at leastone TTI before and after the activating or the deactivating.
 7. Themethod of claim 6, wherein determining the latency comprises at leastone of: determining a first latency when the UE is not communicatingwith the cell using legacy communications or ULL communications beforethe activating; or determining a second latency when the UE iscommunicating with the cell using one of legacy communications or ULLcommunications before the activating, where the second latency is lessthe first latency.
 8. The method of claim 6, wherein determining thelatency comprises at least one of: determining a first latency when theUE is not communicating with the cell using legacy communications or ULLcommunications after the deactivating; or determining a second latencywhen the UE is communicating with the cell using one of legacycommunications or ULL communications after the deactivating, where thesecond latency is less the first latency.
 9. The method of claim 1,wherein communicating with the at least one of the primary cell or thesecondary cell for ULL communications comprises communicating with theat least one of the primary cell or the secondary cell using the ULLcommunications for both downlink communications and uplinkcommunications.
 10. The method of claim 1, wherein communicating withthe at least one of the primary cell or the secondary cell for ULLcommunications comprises communicating with the at least one of theprimary cell or the secondary cell using the ULL communications foreither downlink communications or uplink communications.
 11. The methodof claim 1, wherein the second TTI comprises at least one of one symbol,two symbols, or a slot.
 12. An apparatus for managing ultra low latency(ULL) communications over a plurality of component carriers (CC),comprising: at least one processor; and a memory communicatively coupledwith the at least one processor; wherein the at least one processor isconfigured to: receive a configuration for aggregating a set of CCs,wherein the set of CCs includes at least a primary cell and a secondarycell; communicate, based on the received configuration, with at leastthe primary cell for legacy communications, wherein the legacycommunications are based on a first transmission time interval (TTI)having a first duration; and communicate, based on the receivedconfiguration, with at least one of the primary cell or the secondarycell for ULL communications, wherein the ULL communications are based ona second TTI having a second duration that is less than the firstduration.
 13. The apparatus of claim 12, wherein the at least oneprocessor is further configured to communicate, based on the receivedconfiguration, with the secondary cell for legacy communications. 14.The apparatus of claim 13, wherein the apparatus further comprises atransceiver, the at least one processor communicatively coupled with thetransceiver, via a bus, for communicating signals in a wireless network,and wherein the at least one processor is further configured to receive,via the transceiver, the configuration at least in part through anactivation command for the at least one of the primary cell or thesecondary cell for activating legacy communications with the at leastone of the primary cell or the secondary cell.
 15. The apparatus ofclaim 12, wherein the at least one processor is configured to receive adeactivation command for ULL communications with at least one of theprimary cell or the secondary cell.
 16. The apparatus of claim 15,wherein the at least one processor is further configured to receive anactivation command for activating legacy communications with the atleast one of the primary cell or the secondary cell, along withdeactivating ULL communications with the at least one of the primarycell or the secondary cell.
 17. The apparatus of claim 12, wherein theat least one processor is further configured to determine a latency foractivating or deactivating legacy or ULL communications with the atleast one of the primary cell or the secondary cell, where the latencyis a function of at least one of: whether the activating or thedeactivating is for communications based on the first TTI or the secondTTI, or whether the UE communicates with a cell using at least one TTIbefore and after the activating or the deactivating.
 18. The apparatusof claim 17, wherein the latency is determined to be: a first latencywhen the UE is not communicating with the cell using legacycommunications or ULL communications before the activating; or a secondlatency when the UE is communicating with the cell using one of legacycommunications or ULL communications before the activating, where thesecond latency is less the first latency.
 19. The apparatus of claim 17,wherein the latency is determined to be: a first latency when the UE isnot communicating with the cell using legacy communications or ULLcommunications after the deactivating; or a second latency when the UEis communicating with the cell using one of legacy communications or ULLcommunications after the deactivating, where the second latency is lessthe first latency.
 20. The apparatus of claim 12, wherein the at leastone processor is configured to communicate with the at least one of theprimary cell or the secondary cell for ULL communications at least inpart by communicating with the at least one of the primary cell or thesecondary cell using ULL communications for both downlink communicationsand uplink communications.
 21. The apparatus of claim 12, wherein the atleast one processor is configured to communicate with the at least oneof the primary cell or the secondary cell using ULL communications foreither downlink communications or uplink communications.
 22. Theapparatus of claim 12, wherein the second TTI comprises at least one ofone symbol, two symbols, or a slot.
 23. An apparatus for managing ultralow latency (ULL) communications over a plurality of component carriers(CC), comprising: means for receiving a configuration for aggregating aset of CCs, wherein the set of CCs includes at least a primary cell anda secondary cell; means for communicating, based on the receivedconfiguration, with at least the primary cell for legacy communications,wherein the legacy communications are based on a first transmission timeinterval (TTI) having a first duration; and means for communicating,based on the received configuration, with at least one of the primarycell or the secondary cell for ULL communications, wherein the ULLcommunications are based on a second TTI having a second duration thatis less than the first duration.
 24. The apparatus of claim 23, furthercomprising: means for communicating, based on the receivedconfiguration, with the secondary cell for legacy communications. 25.The apparatus of claim 24, wherein the receiving further comprises:means for receiving an activation command for the at least one of theprimary cell or the secondary cell for activating legacy communicationswith the at least one of the primary cell or the secondary cell.
 26. Theapparatus of claim 23, further comprising means for receiving adeactivation command for ULL communications with the at least one of theprimary cell or the secondary cell.
 27. A computer-readable storagemedium comprising computer-executable code to manage ultra low latency(ULL) communications over a plurality of component carriers (CC),comprising code to: receive a configuration for aggregating a set ofCCs, wherein the set of CCs includes at least a primary cell and asecondary cell; communicate, based on the received configuration, withat least the primary cell for legacy communications, wherein the legacycommunications are based on a first transmission time interval (TTI)having a first duration; and communicate, based on the receivedconfiguration, with at least one of the primary cell or the secondarycell for ULL communications, wherein the ULL communications are based ona second TTI having a second duration that is less than the firstduration.
 28. The computer-readable storage medium of claim 27, furthercomprising code to: communicate, based on the received configuration,with the secondary cell for legacy communications.
 29. Thecomputer-readable storage medium of claim 28, further comprising codeto: receive an activation command for the at least one of the primarycell or the secondary cell for activating legacy communications with theat least one of the primary cell or the secondary cell.
 30. Thecomputer-readable storage medium of claim 27, further comprising code toreceive a deactivation command for ULL communications with the at leastone of the primary cell or the secondary cell.